So I started yesterday and posted a bunch of books.  I just posted a bunch more and apparently 4 of them are on wish lists.  It says they are being held.  Does this mean that someone has been notified that I have the book and if they still want it? 

Duh. That's what it says.  I meant to ask do they just keep going down the wish list line until someone want the book.  And if so, does that mean no one else can request it?

Mary, the Help Center describes this process (Look up "How the Wish List works" for details.)

The first person in the WL line will be offered the book, and it will be held for two days (and until the next PBS processing time, usually overnight). If that person declines (or does not respond) the offer will roll over to the next person in line, who will have the same amount of time to respond, etc.

No one else can request the book from your shelf while it's on WL hold. It's assumed that the book is pending the transaction, so it won't appear when others browse your shelf.

Does this answer your question?

ETA: Also, I thought I'd point out the "Live Help" feature in the Help Center. Feel free to PM the tour guides who are online when you are to ask a question. Don't hesitate to do that! That's what they've volunteered to do! :)

"until the next PBS processing time"

Sigh.  That means more like 3 days, in my case!  Even though my book  "timed out"  early this morning (not requested), it still hasn't moved on to the next person. 

Forgive me for being so antsy,  I'm just out of credits and anxious to send out this book!   bleh   : P